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Remove hard-coded values wherever possible;

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Make most of the station parameters configurable outside
the attenuation functions with the ultimate goal of exposing
them via the property tree
This commit is contained in:
adrian 2011-12-01 13:34:34 +02:00
parent 0c66ca6785
commit 1c1e954de2
2 changed files with 31 additions and 60 deletions
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86
src/Radio/radio.cxx
View file

@ -23,8 +23,7 @@
#endif #endif
#include <math.h> #include <math.h>
#define NDEBUG
#include <assert.h>
#include <stdlib.h> #include <stdlib.h>
#include <deque> #include <deque>
#include "radio.hxx" #include "radio.hxx"
@ -37,15 +36,10 @@
FGRadioTransmission::FGRadioTransmission() { FGRadioTransmission::FGRadioTransmission() {
/** radio parameters (which should probably be set for each radio) */
_receiver_sensitivity = -110.0; // typical AM receiver sensitivity seems to be 0.8 microVolt at 12dB SINAD _receiver_sensitivity = -110.0; // typical AM receiver sensitivity seems to be 0.8 microVolt at 12dB SINAD
/** AM transmitter power in dBm. /** AM transmitter power in dBm.
* Note this value is calculated from the typical final transistor stage output
* small aircraft have portable transmitters which operate at 36 dBm output (4 Watts) others operate in the range 10-20 W
* later possibly store this value in aircraft description
* ATC comms usually operate high power equipment, thus making the link asymetrical; this is taken care of in propagation routines
* Typical output powers for ATC ground equipment, VHF-UHF: * Typical output powers for ATC ground equipment, VHF-UHF:
* 40 dBm - 10 W (ground, clearance) * 40 dBm - 10 W (ground, clearance)
* 44 dBm - 20 W (tower) * 44 dBm - 20 W (tower)
@ -59,18 +53,14 @@ FGRadioTransmission::FGRadioTransmission() {
_rx_antenna_height = 2.0; // RX antenna height above ground level _rx_antenna_height = 2.0; // RX antenna height above ground level
/** pilot plane's antenna gain + AI aircraft antenna gain
* real-life gain for conventional monopole/dipole antenna
**/
_antenna_gain = 2.0;
_rx_antenna_gain = 1.0; _rx_antenna_gain = 1.0; // gain expressed in dBi
_tx_antenna_gain = 1.0; _tx_antenna_gain = 1.0;
_rx_line_losses = 2.0; // to be configured for each station _rx_line_losses = 2.0; // to be configured for each station
_tx_line_losses = 2.0; _tx_line_losses = 2.0;
_propagation_model = 2; // choose between models via option: realistic radio on/off _propagation_model = 2;
_terrain_sampling_distance = fgGetDouble("/sim/radio/sampling-distance", 90.0); // regular SRTM is 90 meters _terrain_sampling_distance = fgGetDouble("/sim/radio/sampling-distance", 90.0); // regular SRTM is 90 meters
} }
@ -124,10 +114,16 @@ double FGRadioTransmission::receiveNav(SGGeod tx_pos, double freq, int transmiss
void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_air) { void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, int ground_to_air) {
if(ground_to_air == 1) {
_transmitter_power += 6.0;
_tx_antenna_height += 30.0;
_tx_antenna_gain += 3.0;
}
double comm1 = getFrequency(1); double comm1 = getFrequency(1);
double comm2 = getFrequency(2); double comm2 = getFrequency(2);
if ( !(fabs(freq - comm1) <= 0.0001) && !(fabs(freq - comm2) <= 0.0001) ) { if ( !(fabs(freq - comm1) <= 0.0001) && !(fabs(freq - comm2) <= 0.0001) ) {
//cerr << "Frequency not tuned: " << freq << " Radio1: " << comm1 << " Radio2: " << comm2 << endl;
return; return;
} }
else { else {
@ -139,13 +135,10 @@ void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, in
// TODO: free space, round earth // TODO: free space, round earth
double signal = LOS_calculate_attenuation(tx_pos, freq, ground_to_air); double signal = LOS_calculate_attenuation(tx_pos, freq, ground_to_air);
if (signal <= 0.0) { if (signal <= 0.0) {
SG_LOG(SG_GENERAL, SG_BULK, "Signal below receiver minimum sensitivity: " << signal);
//cerr << "Signal below receiver minimum sensitivity: " << signal << endl;
return; return;
} }
else { else {
SG_LOG(SG_GENERAL, SG_BULK, "Signal completely readable: " << signal);
//cerr << "Signal completely readable: " << signal << endl;
fgSetString("/sim/messages/atc", text.c_str()); fgSetString("/sim/messages/atc", text.c_str());
/** write signal strength above threshold to the property tree /** write signal strength above threshold to the property tree
* to implement a simple S-meter just divide by 3 dB per grade (VHF norm) * to implement a simple S-meter just divide by 3 dB per grade (VHF norm)
@ -157,8 +150,6 @@ void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, in
// Use ITM propagation model // Use ITM propagation model
double signal = ITM_calculate_attenuation(tx_pos, freq, ground_to_air); double signal = ITM_calculate_attenuation(tx_pos, freq, ground_to_air);
if (signal <= 0.0) { if (signal <= 0.0) {
SG_LOG(SG_GENERAL, SG_BULK, "Signal below receiver minimum sensitivity: " << signal);
//cerr << "Signal below receiver minimum sensitivity: " << signal << endl;
return; return;
} }
if ((signal > 0.0) && (signal < 12.0)) { if ((signal > 0.0) && (signal < 12.0)) {
@ -188,8 +179,6 @@ void FGRadioTransmission::receiveATC(SGGeod tx_pos, double freq, string text, in
fgSetDouble("/sim/sound/voices/voice/volume", old_volume); fgSetDouble("/sim/sound/voices/voice/volume", old_volume);
} }
else { else {
SG_LOG(SG_GENERAL, SG_BULK, "Signal completely readable: " << signal);
//cerr << "Signal completely readable: " << signal << endl;
fgSetString("/sim/messages/atc", text.c_str()); fgSetString("/sim/messages/atc", text.c_str());
/** write signal strength above threshold to the property tree /** write signal strength above threshold to the property tree
* to implement a simple S-meter just divide by 3 dB per grade (VHF norm) * to implement a simple S-meter just divide by 3 dB per grade (VHF norm)
@ -233,16 +222,11 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
double clutter_loss = 0.0; // loss due to vegetation and urban double clutter_loss = 0.0; // loss due to vegetation and urban
double tx_pow = _transmitter_power; double tx_pow = _transmitter_power;
double ant_gain = _antenna_gain; double ant_gain = _rx_antenna_gain + _tx_antenna_gain;
double signal = 0.0; double signal = 0.0;
if(transmission_type == 1)
tx_pow = _transmitter_power + 6.0;
if((transmission_type == 1) || (transmission_type == 3)) double link_budget = tx_pow - _receiver_sensitivity - _rx_line_losses - _tx_line_losses + ant_gain;
ant_gain = _antenna_gain + 3.0; //pilot plane's antenna gain + ground station antenna gain
double link_budget = tx_pow - _receiver_sensitivity + ant_gain;
FGScenery * scenery = globals->get_scenery(); FGScenery * scenery = globals->get_scenery();
@ -259,11 +243,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
SGGeoc center = SGGeoc::fromGeod( max_own_pos ); SGGeoc center = SGGeoc::fromGeod( max_own_pos );
SGGeoc own_pos_c = SGGeoc::fromGeod( own_pos ); SGGeoc own_pos_c = SGGeoc::fromGeod( own_pos );
/** position of sender radio antenna (HAAT)
sender can be aircraft or ground station
**/
double ATC_HAAT = 30.0;
double Aircraft_HAAT = 5.0;
double sender_alt_ft,sender_alt; double sender_alt_ft,sender_alt;
double transmitter_height=0.0; double transmitter_height=0.0;
double receiver_height=0.0; double receiver_height=0.0;
@ -302,7 +282,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
double elevation_under_pilot = 0.0; double elevation_under_pilot = 0.0;
if (scenery->get_elevation_m( max_own_pos, elevation_under_pilot, NULL )) { if (scenery->get_elevation_m( max_own_pos, elevation_under_pilot, NULL )) {
receiver_height = own_alt - elevation_under_pilot + 3; //assume antenna located 3 meters above ground receiver_height = own_alt - elevation_under_pilot;
} }
double elevation_under_sender = 0.0; double elevation_under_sender = 0.0;
@ -313,10 +293,10 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
transmitter_height = sender_alt; transmitter_height = sender_alt;
} }
if(transmission_type == 1)
transmitter_height += ATC_HAAT; transmitter_height += _tx_antenna_height;
else receiver_height += _rx_antenna_height;
transmitter_height += Aircraft_HAAT;
SG_LOG(SG_GENERAL, SG_BULK, SG_LOG(SG_GENERAL, SG_BULK,
"ITM:: RX-height: " << receiver_height << " meters, TX-height: " << transmitter_height << " meters, Distance: " << distance_m << " meters"); "ITM:: RX-height: " << receiver_height << " meters, TX-height: " << transmitter_height << " meters, Distance: " << distance_m << " meters");
@ -383,7 +363,7 @@ double FGRadioTransmission::ITM_calculate_attenuation(SGGeod pos, double freq, i
} }
double num_points= (double)_elevations.size(); double num_points= (double)_elevations.size();
//cerr << "ITM:: Max alt between: " << max_alt_between << ", num points:" << num_points << endl;
_elevations.push_front(point_distance); _elevations.push_front(point_distance);
_elevations.push_front(num_points -1); _elevations.push_front(num_points -1);
int size = _elevations.size(); int size = _elevations.size();
@ -442,7 +422,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m; double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m;
// First Fresnel radius // First Fresnel radius
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (itm_elev[0] - j) * itm_elev[1] / 1000000) / ( distance_m * freq / 1000) ); double frs_rad = 548 * sqrt( (j * itm_elev[1] * (itm_elev[0] - j) * itm_elev[1] / 1000000) / ( distance_m * freq / 1000) );
assert(frs_rad > 0);
//double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3 //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
@ -494,7 +473,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[num_points_1st + 2] + clutter_height) / distance_m; double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[num_points_1st + 2] + clutter_height) / distance_m;
// First Fresnel radius // First Fresnel radius
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_1st - j) * itm_elev[1] / 1000000) / ( num_points_1st * itm_elev[1] * freq / 1000) ); double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_1st - j) * itm_elev[1] / 1000000) / ( num_points_1st * itm_elev[1] * freq / 1000) );
assert(frs_rad > 0);
//double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3 //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
@ -539,7 +517,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
double grad = fabs(itm_elev[last+1] + clutter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m; double grad = fabs(itm_elev[last+1] + clutter_height - itm_elev[(int)itm_elev[0] + 2] + receiver_height) / distance_m;
// First Fresnel radius // First Fresnel radius
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_2nd - j) * itm_elev[1] / 1000000) / ( num_points_2nd * itm_elev[1] * freq / 1000) ); double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_2nd - j) * itm_elev[1] / 1000000) / ( num_points_2nd * itm_elev[1] * freq / 1000) );
assert(frs_rad > 0);
//double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3 //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
@ -592,7 +569,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[num_points_1st + 2] + clutter_height) / distance_m; double grad = fabs(itm_elev[2] + transmitter_height - itm_elev[num_points_1st + 2] + clutter_height) / distance_m;
// First Fresnel radius // First Fresnel radius
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_1st - j) * itm_elev[1] / 1000000) / ( num_points_1st * itm_elev[1] * freq / 1000) ); double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_1st - j) * itm_elev[1] / 1000000) / ( num_points_1st * itm_elev[1] * freq / 1000) );
assert(frs_rad > 0);
//double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3 //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
@ -637,7 +613,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
// First Fresnel radius // First Fresnel radius
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_2nd - j) * itm_elev[1] / 1000000) / ( num_points_2nd * itm_elev[1] * freq / 1000) ); double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_2nd - j) * itm_elev[1] / 1000000) / ( num_points_2nd * itm_elev[1] * freq / 1000) );
assert(frs_rad > 0);
//double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3 //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
double min_elev = SGMiscd::min(itm_elev[last+1] + clutter_height, itm_elev[num_points_1st + num_points_2nd +2] + clutter_height); double min_elev = SGMiscd::min(itm_elev[last+1] + clutter_height, itm_elev[num_points_1st + num_points_2nd +2] + clutter_height);
@ -682,7 +657,6 @@ void FGRadioTransmission::clutterLoss(double freq, double distance_m, double itm
// First Fresnel radius // First Fresnel radius
double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_3rd - j) * itm_elev[1] / 1000000) / ( num_points_3rd * itm_elev[1] * freq / 1000) ); double frs_rad = 548 * sqrt( (j * itm_elev[1] * (num_points_3rd - j) * itm_elev[1] / 1000000) / ( num_points_3rd * itm_elev[1] * freq / 1000) );
assert(frs_rad > 0);
//double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3 //double earth_h = distance_m * (distance_m - j * itm_elev[1]) / ( 1000000 * 12.75 * 1.33 ); // K=4/3
@ -847,10 +821,9 @@ double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, i
frq_mhz = freq; frq_mhz = freq;
double dbloss; double dbloss;
double tx_pow = _transmitter_power; double tx_pow = _transmitter_power;
double ant_gain = _antenna_gain; double ant_gain = _rx_antenna_gain + _tx_antenna_gain;
double signal = 0.0; double signal = 0.0;
double ATC_HAAT = 30.0;
double Aircraft_HAAT = 5.0;
double sender_alt_ft,sender_alt; double sender_alt_ft,sender_alt;
double transmitter_height=0.0; double transmitter_height=0.0;
double receiver_height=0.0; double receiver_height=0.0;
@ -859,13 +832,8 @@ double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, i
double own_alt_ft = fgGetDouble("/position/altitude-ft"); double own_alt_ft = fgGetDouble("/position/altitude-ft");
double own_alt= own_alt_ft * SG_FEET_TO_METER; double own_alt= own_alt_ft * SG_FEET_TO_METER;
if(transmission_type == 1)
tx_pow = _transmitter_power + 6.0;
if((transmission_type == 1) || (transmission_type == 3)) double link_budget = tx_pow - _receiver_sensitivity - _rx_line_losses - _tx_line_losses + ant_gain;
ant_gain = _antenna_gain + 3.0; //pilot plane's antenna gain + ground station antenna gain
double link_budget = tx_pow - _receiver_sensitivity + ant_gain;
//cerr << "ITM:: pilot Lat: " << own_lat << ", Lon: " << own_lon << ", Alt: " << own_alt << endl; //cerr << "ITM:: pilot Lat: " << own_lat << ", Lon: " << own_lon << ", Alt: " << own_alt << endl;
@ -881,10 +849,10 @@ double FGRadioTransmission::LOS_calculate_attenuation(SGGeod pos, double freq, i
double distance_m = SGGeodesy::distanceM(own_pos, sender_pos); double distance_m = SGGeodesy::distanceM(own_pos, sender_pos);
if(transmission_type == 1)
transmitter_height += ATC_HAAT; transmitter_height += _tx_antenna_height;
else receiver_height += _rx_antenna_height;
transmitter_height += Aircraft_HAAT;
/** radio horizon calculation with wave bending k=4/3 */ /** radio horizon calculation with wave bending k=4/3 */
double receiver_horizon = 4.12 * sqrt(receiver_height); double receiver_horizon = 4.12 * sqrt(receiver_height);

5
src/Radio/radio.hxx
View file

@ -44,7 +44,6 @@ private:
double _transmitter_power; double _transmitter_power;
double _tx_antenna_height; double _tx_antenna_height;
double _rx_antenna_height; double _rx_antenna_height;
double _antenna_gain;
double _rx_antenna_gain; double _rx_antenna_gain;
double _tx_antenna_gain; double _tx_antenna_gain;
double _rx_line_losses; double _rx_line_losses;
@ -72,6 +71,10 @@ public:
void setRxSensitivity(double sensitivity) { _receiver_sensitivity = sensitivity; }; void setRxSensitivity(double sensitivity) { _receiver_sensitivity = sensitivity; };
void setTxAntennaHeight(double tx_antenna_height) { _tx_antenna_height = tx_antenna_height; }; void setTxAntennaHeight(double tx_antenna_height) { _tx_antenna_height = tx_antenna_height; };
void setRxAntennaHeight(double rx_antenna_height) { _rx_antenna_height = rx_antenna_height; }; void setRxAntennaHeight(double rx_antenna_height) { _rx_antenna_height = rx_antenna_height; };
void setTxAntennaGain(double tx_antenna_gain) { _tx_antenna_gain = tx_antenna_gain; };
void setRxAntennaGain(double rx_antenna_gain) { _rx_antenna_gain = rx_antenna_gain; };
void setTxLineLosses(double tx_line_losses) { _tx_line_losses = tx_line_losses; };
void setRxLineLosses(double rx_line_losses) { _rx_line_losses = rx_line_losses; };
void setPropagationModel(int model) { _propagation_model = model; }; void setPropagationModel(int model) { _propagation_model = model; };
// transmission_type: 0 for air to ground 1 for ground to air, 2 for air to air, 3 for pilot to ground, 4 for pilot to air // transmission_type: 0 for air to ground 1 for ground to air, 2 for air to air, 3 for pilot to ground, 4 for pilot to air
void receiveATC(SGGeod tx_pos, double freq, string text, int transmission_type); void receiveATC(SGGeod tx_pos, double freq, string text, int transmission_type);